U.S. Vice President Joe Biden is traveling Wednesday to Croatia to discuss the influx of migrants, energy issues and the fight against terrorism with Croatian officials and European Council President Donald Tusk.

Those meetings will happen on the sidelines of a summit of Southeastern European leaders in Zagreb hosted by Croatian President Kolinda Grabar-Kitarovic and Slovenian President Borut Pahor.

Fact Sheet: U.S. Assistance to the Western Balkans

The leaders of Croatia, Serbia, Bosnia and Herzegovina, Kosovo, Macedonia and Albania are also taking part in the summit that is expected to be dominated by discussion of the thousands of migrants reaching European shores every day.

In the past week, Croatia, Slovenia, Serbia and Macedonia have all announced new restrictions to allow only what they call war-zone refugees from Syria, Iraq and Afghanistan to move through their countries. The limits have led to days of migrant protests and calls from the United Nations and International Organization for Migration for those countries to re-establish coordination mechanisms and help provide safe routes of passage for people uprooted by conflict.

FILE - Macedonian policemen stand guard as a woman and a kid pass from the northern Greek village of Idomeni to southern Macedonia, Nov. 20, 2015.

The Croatian and Slovenian leaders met ahead of the summit and stressed the need to come up with a humane solution that significantly cuts the number of migrants passing through the Balkans.

The Wednesday summit, as well as Biden's meetings with Tusk and Grabar-Kitarovic, will also cover security issues raised by conflicts in the Middle East and Ukraine.